Packmanuk, you said that you will have £400,000 which will be circa $800,000, You would be best going for one of the Government Investment Schemes that would cost $500,000 this would give you your green card, so you could work at what you wanted and have $300,000 left to do what you want and with this scheme they pay you a % of your investment very month too.
DM me for more details.